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JIPMER Jipmer Medical Solved Paper-2002

  • question_answer
    If potential difference across a capacitor is changed from 15 V to 30 V, work done is W. The work done when potential difference is changed from 30 V to 60 V, will be:

    A)  W                                          

    B)  4 W                      

    C)  3 W                      

    D)         2 W

    Correct Answer: B

    Solution :

    From relation of work done \[W=\frac{1}{2}C{{V}^{2}},\]    so   \[W\propto {{V}^{2}}\] As \[{{V}_{2}}=60-30=30\,V,\]    \[{{V}_{1}}=30-15=15\,V\] hence \[\frac{{{W}_{2}}}{{{W}_{1}}}={{\left( \frac{{{V}_{2}}}{V{{ & }_{1}}} \right)}^{2}}\] or            \[{{W}_{2}}={{\left( \frac{30}{15} \right)}^{2}}W\]                            \[{{W}_{1}}=W\] \[{{W}_{2}}=4\,W\]


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